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Gray cast iron inoculant

a technology of inoculant and gray cast iron, which is applied in the field of manufacturing of cast iron, can solve the problems of constant formation of iron carbides infoundries, add to the cost of producing cast iron products, etc., and achieve the effects of improving gray iron microstructure, reducing carbide content, and increasing cell coun

Active Publication Date: 2017-10-19
ELKEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text describes a method for reducing slag buildup in the casting process by using an inoculant with low calcium content. By adding aluminum to the inoculant and inoculating the molten iron in the transfer ladle or the pouring unit, the chill is reduced and the amount of slag buildup is reduced. The inoculant with high aluminum content improves the microstructures and mechanical properties of the cast iron without adding extra cost for slag removal or secondary alloys. The use of the inoculant with low calcium content was surprising and unexpected in its ability to reduce chill and slag formation in the transfer ladle and ultimately slag buildup in the pouring unit.

Problems solved by technology

If the carbon takes the form of iron carbide, then the cast iron is referred to as white cast iron and has the physical characteristics of being hard and brittle which in certain applications is undesirable.
In cast iron production the foundries are constantly plagued by the formation of iron carbides in thin sections of the castings.
However, this has shown to create problems due to slag build up in the pouring unit probably caused by the high calcium content in the Alinoc® inoculant.
The pouring unit can thus only be used for a limited number of cast iron melts and thus adds to the costs for producing cast iron products.

Method used

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  • Gray cast iron inoculant
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Examples

Experimental program
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Effect test

example 1

[0057]First rounds of testing used an inoculant according to the present invention containing 2% by weight aluminum in the alloy. Iron castings were produced with acceptable levels of carbides and slag buildup was not a problem. Below is a round of testing showing the difference between final aluminum of 0.006% and 0.012% Al in the cast iron, with the former being fully carbidic and the latter having carbide free or only trace amounts of carbide which is acceptable in this casting. No other significant changes were made to the process. FIG. 1 illustrates the results. No carbides were found in samples A and E inoculated with the inoculant according to the present invention. As can be seen from samples B and F in FIG. 1 the cast iron structure contains carbide.

example 2

[0058]The occurrence of a hard slag buildup developed shortly after adding an inoculant (Alinoc®) with a calcium content of 0.5 to 1.5%, mainly occurring under the iron level on the walls of the pouring unit leading to shortened life and extra cleaning costs. FIG. 2 illustrates a pouring unit with low hours of use, while FIG. 3 illustrates a pouring unit with build-up of slag on the sidewalls when Alinoc® inoculant where added to the transfer ladle and Superseed® Extra inoculant with Al content <0.5% by weight were added to the pouring unit.

[0059]One test was done with inoculating the cast iron melt with Superseed® Extra inoculant with Al content <0.5% by weight and with the inoculant according to the present invention together with Superseed® Extra inoculant with Al content <0.5% by weight. As shown in FIGS. 4 and 5 little or no slag build-up was found in the pouring unit.

[0060]Since molten cast-iron and slag coexists it was desirable to look at the chemistry of the slag in pouring...

example 3

[0067]Two different inoculants according to the invention were produced.

[0068]Inoculant A had the following composition: 73.1% by weight Si, 1.94% by weight Al, 0.10% by weight Ca, 1.19% by weight Zr, 0.99% by weight Sr, the remaining being Fe.

[0069]Inoculant B had the following composition: 71.3% by weight Si, 4.4% by weight Al, 0.085 Ca, 1.27% by weight Zr, 0.98% by weight Sr, the remaining being iron.

[0070]Inoculant A according to the invention was added to a cast iron melt in the pouring ladle as the only inoculant in an amount of 0.3% by weight based on the weight of the base cast iron and Inoculant B was added to a cast iron melt in the pouring ladle as the only inoculant in an amount of 0.3% by weight based on the weight of the base cast iron.

[0071]For comparison purposes the base cast iron was inoculated with Superseed® Extra inoculant containing less than 0.5% by weight Al, denoted Inoculant C.

[0072]The base cast iron had the following composition: 3.45° % by weight C, 1.82...

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Abstract

A ferrosilicon inoculant for gray cast iron containing between 0.1 to 10% by weight strontium, less than 0.35% by weight calcium, 1.5 to 10% by weight aluminum and 0.1 to 15% zirconium, The inoculant, method for producing the inoculant, method for inoculating the melt and a gray cast iron inoculated with the inoculant are covered.

Description

BACKGROUND OF THE INVENTION[0001]The invention relates to the manufacture of cast iron and more particularly to an inoculant for gray cast iron to improve the overall properties thereof.[0002]Cast iron is typically produced in a cupola or induction furnace, and generally has about 2 to 4 percent carbon. The carbon is intimately mixed in with the iron and the form which the carbon takes in the solidified cast iron is very important to the characteristics of the cast iron. If the carbon takes the form of iron carbide, then the cast iron is referred to as white cast iron and has the physical characteristics of being hard and brittle which in certain applications is undesirable. If the carbon takes the form of graphite, the cast iron is soft and machine-able and is referred to as gray cast iron.[0003]Graphite may occur in cast iron in the flake, vermicular, nodular or spherical forms and variations thereof. The nodular or spherical form produces the highest strength and most ductile for...

Claims

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Application Information

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IPC IPC(8): C22C33/08C22C37/10C21C1/08
CPCC22C33/08C22C37/10C21C1/08C22C33/06
Inventor LIPTAK, MATTHEW
Owner ELKEM